Observation: East Bowl

Observation Date
Observer Name
Salt Lake » Big Cottonwood Canyon » Silver Fork » East Bowl
Location Name or Route
East Bowl of Silver Fork
Light Snowfall
Wind Direction
Wind Speed
Weather Comments
A period of riming in the afternoon that froze on goggles and jackets.
Snow Characteristics
New Snow Depth
New Snow Density
Snow Surface Conditions
Snow Characteristics Comments
2-3 cms of dense new snow with some rimed crystals. The dense snow made for easy travel and fun riding conditions.
Red Flags
Red Flags
Recent Avalanches
Poor Snowpack Structure
Red Flags Comments
We found a poor snowpack structure on west aspects above 10,000 with a thin slab on top of weak facets. There was also a reported avalanche from Wednesday, Jan 24 in East Bowl.
Avalanche Problem #1
Persistent Weak Layer
Decreasing Danger
Problem #1 Comments
Thoughts in the comments below.
Snow Profile
The PWL that is found on most aspects and all elevations continues to gain strength with stronger hand-hardness tests, evidence of rounding, and higher ECT scores. In areas where the slab over the PWL is deep (over a meter), it is a strong 1F-hard slab and the PWL is 4F. Much of the central Wasatch (especially the upper Cottonwoods) has this structure and this is certainly a good sign. In areas where the snowpack is deeper (again, the upper Cottonwoods), the danger is likely Moderate (where human-triggered avalanches are possible with large avalanches in isolated areas.)
Today, we found a thinner snowpack on west aspects in upper elevations of East Bowl of Silver Fork. There was an avalanche on a steep west-facing slope in East Bowl on Wednesday and we decided it was too dangerous to approach the crown. But digging pits on similar adjacent slopes, we found a shallower snowpack (120 cms) where the slab on top of the facets was 45-60 cms thick. We got full propagation on five extended column tests, failing between 21 and 25 taps down in the PWL. We also got a small, localized collapse just off of a ridgeline in a thinner snowpack area.
Given the red flags of (1) recent avalanches and (2) poor snowpack structure, we traveled cautiously and avoided steeper slopes.
As we move towards a Moderate avalanche danger, I will evaluate slopes and continue to avoid thinner snowpack areas where triggering an avalanche on the PWL is more likely.
Photo of pit in thinner snowpack area.
Although snow amounts were unfortunately meager, the few cms had bonded poorly to the old snow surface on all aspects. This will only be an issue if we get additional snow where any soft slabs may be reactive at the old snow/new snow interface.
Today's Observed Danger Rating
Tomorrows Estimated Danger Rating